I would rather have physical buttons, myself. In fact, I want page forward and back on both sides of the device, like on many of the Kindles. Turning pages is often the only thing I want to do with the device, why waste battery life running a touchscreen the whole time?

I suspect that the power usage of the IR touchscreen used by most of the current generation of readers, is utterly negligible compared to the overall power usage of the device.